定义一个userDao接口:UserDao
package com.spring;
public interface UserDao {
public void getUser();
}
定义一个userDao接口实现类(基于mysql):UserMysqlDaoImpl
package com.spring;
public class UserMysqlDaoImpl implements UserDao{
@Override
public void getUser() {
System.out.println("调用了Mysql数据驱动");
}
}
定义一个userDao接口实现类(基于oracle):UserOracleDaoImpl
package com.spring;
public class UserOracleDaoImpl implements UserDao{
@Override
public void getUser() {
System.out.println("调用了oracle数据驱动");
}
}
定义一个UserService接口:UserService
package com.spring;
public interface UserService {
public void getUser();
}
定义一个UserService接口实现类:UserServiceImpl
package com.spring;
public class UserServiceImpl implements UserService{
UserDao userDao = new UserMysqlDaoImpl();//mysql实现
//UserDao userDao = new UserOracleDaoImpl();//oracle实现
@Override
public void getUser() {
userDao.getUser();
}
}
编写测试类:
public static void main(String[] args) {
UserService userService = new UserServiceImpl();
userService.getUser();
}
解释:
1:如果我们要在UserServiceImpl 调用userDao的业务实现,必须要new 一个对象
2:如果我们要修改UserServiceImpl 调用userDao的业务实现,必须要重新new一个对象
3:以上两点让代码紧耦合,而且对代码的管理增加了难度,要不停的修改代码
基于传统业务调用编程的UserDao 、UserMysqlDaoImpl 、UserOracleDaoImpl、UserService
修改UserService接口实现类:UserServiceImpl
package com.spring;
public class UserServiceImpl implements UserService{
private UserDao userDao;//定义要调用的接口变量
//给这个变量增加set方法(重点)
public void setUserDao(UserDao userDao) {
this.userDao = userDao;
}
@Override
public void getUser() {
userDao.getUser();
}
}
编写测试类:
public static void main(String[] args) {
UserService userService = new UserServiceImpl();
//通过set方法注入不同的业务实现
((UserServiceImpl) userService).setUserDao(new UserOracleDaoImpl());
userService.getUser();
}
基于IOC 编码式业务调用编程的UserDao 、UserMysqlDaoImpl 、UserOracleDaoImpl、UserService、UserServiceImpl
在resources类目录下创建spring配置文件beans.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
<!--mysql业务实现-->
<bean id="userMysqlDao" class="com.spring.UserMysqlDaoImpl"></bean>
<!--oracle业务实现-->
<bean id="userOracleDao" class="com.spring.UserOracleDaoImpl"></bean>
<!--ref:引用spring创建好的对象-->
<bean id="userService" class="com.spring.UserServiceImpl">
<property name="userDao" ref="userOracleDao"></property>
</bean>
</beans>
编写测试类:
public static void main(String[] args) {
//获取spring容器
ApplicationContext applicationContext =
new ClassPathXmlApplicationContext("beans.xml");
//通过id获取bean
UserServiceImpl userService =
(UserServiceImpl) applicationContext.getBean("userService");
//调用
userService.getUser();
}
定义一个VO对象:UserVo
package com.spring.Vo;
public class UserVo {
private String userName;//用户名
private String userPass;//密码
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
public String getUserPass() {
return userPass;
}
public void setUserPass(String userPass) {
this.userPass = userPass;
}
}
通过spring容器实例化UserVo对象:
<!--
使用spring来创建对象 在spring中称之为bean
UserVo userVo = new UserVo()
id = 变量名
class = new UserVo()
name = 属性值
value = 属性赋值
-->
<bean id="userVo" class="com.spring.Vo.UserVo">
<property name="userName" value="admin"></property>
<property name="userPass" value="123456"></property>
</bean>
编写测试类:
public static void main(String[] args) {
//获取容器
ApplicationContext applicationContext =
new ClassPathXmlApplicationContext("beans.xml");
//获取bean
UserVo userVo = (UserVo) applicationContext.getBean("userVo");
System.out.println(userVo.getUserName()+userVo.getUserPass());
}
spring实例化bean是基于无参构造方法的,如果加入了有参构造方法,那么set方法就不起作用了,而且bean也会报错(&除非再加一个无参构造器,这样set和构造器实例化bean都可以使用&)!
在UserVo中加入有参构造方法:
public UserVo(String userName, String userPass) {
this.userName = userName;
this.userPass = userPass;
}
sping实例化bean:
<bean id="userVo" class="com.spring.Vo.UserVo">
<constructor-arg index="0" value="admin"></constructor-arg>
<constructor-arg index="1" value="123"></constructor-arg>
</bean>
或者
<bean id="userVo" class="com.spring.Vo.UserVo">
<constructor-arg name="userName" value="admin"></constructor-arg>
<constructor-arg name="userPass" value="123456"></constructor-arg>
</bean>
1:alias:别名
<!--
给userVo 起一个别名为myUser
既可以通过userVo获取到这个bean
也可以通过myUser获取到这个bean
-->
<alias name="userVo" alias="myUser"></alias>
2:bean:实例化对象
<!--
id:bean的唯一标识,相当于类中的变量名
class:bean所对应的的全限定名 包名 + 类名
name:别名 可以定义多个,也可以得到bean对象
-->
<bean id="userVo" class="com.spring.Vo.UserVo" name="u1,u2">
<property name="userName" value="admin"></property>
<property name="userPass" value="12345"></property>
</bean>
3:import:合并配置文件
<!--将多个Spring配置文件合并为一个,用于多人开发-->
<import resource="beans.xml"></import>
依赖:就是spring创建bean; 注入:就是给bean的属性赋值
一、构造器注入(上面已经讲过…….略)
二、Set注入(重点)
可以通过Set接口注入普通类型、对象类型、数组类型、集合类型、map类型、set类型、null类型、Properties类型。
1:定义一个Address Javabean对象(添加get和set以及tostring方法)
package com.spring.Vo;
public class Address {
private String address;
}
2:定义一个StudentJavabean对象(添加get和set以及tostring方法)
package com.spring.Vo;
import java.util.*;
public class Student {
private String name; //普通类型
private Address address; //对象类型
private String[] books; //数组类型
private List<String> hobbys; //集合类型
private Map<String,String> card; //map类型
private Set<String> games;//set类型
private String wife; //null类型
private Properties info; //Properties类型
}
3:创建spring配置文件
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
<!--实例化Address类-->
<bean id="address" class="com.spring.Vo.Address">
<property name="address" value="北京"></property>
</bean>
<!--实例化Student类-->
<bean id="student" class="com.spring.Vo.Student">
<!--第一 普通注入:value-->
<property name="name" value="张三"></property>
<!--第二 bean注入:ref-->
<property name="address" ref="address"></property>
<!--第三 数组注入:array-->
<property name="books">
<array>
<value>语文</value>
<value>数学</value>
<value>英语</value>
</array>
</property>
<!--第四 list集合注入:list-->
<property name="hobbys">
<list>
<value>听歌</value>
<value>看书</value>
<value>跑步</value>
</list>
</property>
<!--第五 map集合注入:map-->
<property name="card">
<map>
<entry key="k1" value="v1"></entry>
<entry key="k2" value="v2"></entry>
</map>
</property>
<!--第六 set集合注入:set-->
<property name="games">
<set>
<value>CS</value>
<value>LoL</value>
</set>
</property>
<!--第七 null集合注入:null-->
<property name="wife">
<null />
</property>
<!--第八 Properties集合注入:props-->
<property name="info">
<props>
<prop key="number" >10001</prop>
<prop key="age">18</prop>
</props>
</property>
</bean>
</beans>
4:编写测试
//获取容器
ApplicationContext applicationContext =
new ClassPathXmlApplicationContext("applicationContext.xml");
//获取bean
Student student = (Student) applicationContext.getBean("student");
System.out.println(student.toString());
5:查看打印结果
Student
{
name='张三',
address=Address{address='北京'},
books=[语文, 数学, 英语],
hobbys=[听歌, 看书, 跑步],
card={k1=v1, k2=v2},
games=[CS, LoL],
wife='null',
info={age=18, number=10001}
}
三、命名空间注入
p命名空间:针对set注入方式
c命名空间:针对构造器注入方式
xmlns:p="http://www.springframework.org/schema/p"
xmlns:c="http://www.springframework.org/schema/c"
1:定义一个UserInfo Javabean对象
package com.spring.Vo;
public class UserInfo {
private String name;
private String age;
public void setName(String name) {
this.name = name;
}
public void setAge(String age) {
this.age = age;
}
/*无参构造器*/
public UserInfo() {
}
/*有参构造器*/
public UserInfo(String name, String age) {
this.name = name;
this.age = age;
}
@Override
public String toString() {
return "UserInfo{" +
"name='" + name + '\'' +
", age='" + age + '\'' +
'}';
}
}
2:创建spring配置文件
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:p="http://www.springframework.org/schema/p"
xmlns:c="http://www.springframework.org/schema/c"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
<!--p命名空间:必须有无参构造方法-->
<bean id="userInfo" class="com.spring.Vo.UserInfo" p:name="admin" p:age="18"></bean>
<!--c命名空间:必须有有参构造方法-->
<bean id="userInfo2" class="com.spring.Vo.UserInfo" c:name="zhangsan" c:age="15"></bean>
</beans>
4:编写测试
@Test
public void test01(){
//获取容器
ApplicationContext applicationContext =
new ClassPathXmlApplicationContext("applicationContext.xml");
//获取bean(试试userInfo)
UserInfo userInfo =applicationContext.getBean("userInfo2", UserInfo.class);
System.out.println(userInfo.toString());
}
四、bean的作用域
1:单例模式(singleton):每次从容器中拿到的对象都是同一个,spring默认值
<bean id="userInfo" class="com.spring.Vo.UserInfo" scope="singleton"></bean>
//获取容器
ApplicationContext applicationContext =
new ClassPathXmlApplicationContext("applicationContext.xml");
//获取bean
UserInfo userInfo01 =applicationContext.getBean("userInfo", UserInfo.class);
UserInfo userInfo02 =applicationContext.getBean("userInfo", UserInfo.class);
System.out.println(userInfo01 == userInfo02);
/*结果:true */
2:原型模式(prototype):每次从容器中拿到的对象都是新的
<bean id="userInfo" class="com.spring.Vo.UserInfo" scope="prototype"></bean>
//获取容器
ApplicationContext applicationContext =
new ClassPathXmlApplicationContext("applicationContext.xml");
//获取bean
UserInfo userInfo01 =applicationContext.getBean("userInfo", UserInfo.class);
UserInfo userInfo02 =applicationContext.getBean("userInfo", UserInfo.class);
System.out.println(userInfo01 == userInfo02);
/*结果:false*/
3:其他模式:request、sessoin、application;只能在web开发中使用
五、bean的自动装配
spring会在上下文中自动寻找,并自动给bean装配属性
在spring中有三种装配方式:
1:在xml总显示的配置
2:隐式的自动装配
3:在java中显示装配
场景:一个人拥有两只宠物
创建三个对象:Dog、Cat、People
package com.spring.vo1;
public class Dog {
/*模拟狗叫*/
public void shout(){
System.out.println("wangwang~~~");
}
}
package com.spring.vo1;
public class Cat {
/*模拟猫叫*/
public void shout(){
System.out.println("miaomiao~~~~");
}
}
package com.spring.vo1;
public class People {
private Dog dog;/*宠物狗*/
private Cat cat;/*宠物猫*/
private String name;/*人的姓名*/
public Dog getDog() {
return dog;
}
public void setDog(Dog dog) {
this.dog = dog;
}
public Cat getCat() {
return cat;
}
public void setCat(Cat cat) {
this.cat = cat;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
spring实例化三个对象:
<bean id="cat" class="com.spring.vo1.Cat"></bean>
<bean id="dog" class="com.spring.vo1.Dog"></bean>
<bean id="people" class="com.spring.vo1.People">
<property name="name" value="king"></property>
<property name="cat" ref="cat"></property>
<property name="dog" ref="dog"></property>
</bean>
测试:
//获取容器
ApplicationContext applicationContext =
new ClassPathXmlApplicationContext("applicationContext.xml");
//获取bean
People people =applicationContext.getBean("people", People.class);
people.getCat().shout();
people.getDog().shout();
输出结果:
miaomiao~~~~
wangwang~~~
把以上场景改为自动装配:autowire
1:byName:自动在上下文中找 和自己对象中定义的属性名对应的bean id(id必须全局唯一)
<bean id="cat" class="com.spring.vo1.Cat"></bean>
<bean id="dog" class="com.spring.vo1.Dog"></bean>
<!--byName:会自动在上下文中找 和自己对象中定义的属性名对应的bean id-->
<bean id="people" class="com.spring.vo1.People" autowire="byName">
<property name="name" value="king"></property>
</bean>
2:byType:自动在上下文中找 和自己对象中定义的属性名的类型对应的bean(class必须全局唯一)
<bean id="cat" class="com.spring.vo1.Cat"></bean>
<bean id="dog" class="com.spring.vo1.Dog"></bean>
<!--byType:会自动在上下文中找 和自己对象中定义的属性名的类型对应的bean-->
<bean id="people" class="com.spring.vo1.People" autowire="byType">
<property name="name" value="king"></property>
</bean>
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